Enhanced Selectivity to Methanol in CO₂ Hydrogenation on CuO/ZrO₂ Catalysts by Alkali Metal Modification

Abstract In order to alleviate the influence of greenhouse effect on global climate change, the effective utilization of CO 2 to prepare fine chemicals should be paid more attention to, however, which is greatly blocked by the catalyst with low efficiency. Here, alkali metal (Li, Na, or K) are employed as a modification aid to prepare CuO/ZrO 2 catalyst for CO 2 hydrogenation to methanol. The effects of alkali metal on physicochemical properties and catalytic activities of CuO/ZrO 2 catalyst were studied in detail by the XRD, N 2 ‐physisorption, ICP‐OES, SEM/EDS, H 2 /N 2 O/CO 2 /NH 3 ‐chemisorption, and evaluation test. The results verified that the use of complex combustion method enabled the uniform combination of all components in precursor. High‐temperature calcination (700 °C) further enhanced the strong interaction and synergistic effect between Cu and ZrO 2 . Most importantly, the introduction of alkali metal effectively altered the structure and catalytic activity of CuO/ZrO 2 catalysts. However, the selectivity to methanol increased while the CO 2 conversion decreased regardless of different kinds of alkali metal being introduced to the CuO/ZrO 2 catalysts. For example, CuO/ZrO 2 catalyst modified by K exhibited excellent performance for methanol production that 98.9% selectivity of methanol based on 8.8% conversion of CO 2 after 48 h online reaction.